Food industry businesses typically use commercial dishwashers to clean the large volume of dirty dishes produced each day. Exemplary commercial dishwashers include batch type dishwashers with a single chamber and conveyor type dishwashers with one or more chambers. Generally, multiple-chamber conveyor dishwashers have one or more wash chambers (e.g., prewash and wash chambers) and one or more rinse chambers (e.g., power rinse and final rinse chambers). To wash the dishes, a conveyor belt carries racks of dishes through each chamber.
To meet health safety standards, e.g., the standards set by NSF International, the final rinse chamber typically sanitizes the dishes using a chemical solution or high temperature water. Dishwashers using a chemical-based final rinse process create chemical waste that may require additional processing to reduce environmental impact. Hot water-based final rinse processes do not create chemical waste, but do require a significant amount of energy to achieve the required relatively high water temperature (e.g., 180° F.). For heating the water sufficiently, the final rinse module in a conventional conveyor type dishwasher may include a so-called booster heater that boosts the temperature of water to the required final temperature. Frequently, the water supplied to the booster heater comes from a high temperature external water source (e.g., the building's hot water heater). However, continuously providing heated water from a high temperature external water source requires significant energy. Commercial dishwasher manufacturers therefore continue to search for environmentally friendly and energy efficient ways to meet the sanitizing requirements of a final rinse stage.